The present invention relates to a semiconductor apparatus. In particular, the present invention relates to a semiconductor apparatus in which a flip-chip packaging technique is used and a method for producing the same.
Recently the semiconductor element has become increasingly integrated, the size of the semiconductor apparatus has become miniaturized and the pitch between the connecting terminals has become narrower. Under these circumstances, the semiconductor apparatus in which the flip-chip packaging technique is used has been developed more and more. Hereinafter, one example of semiconductor apparatus in which the flip-chip packaging technique is used will be explained, referring to the figures.
FIG. 9 is a sectional view showing a semiconductor in which the flip-chip packaging technique is used. An aluminum electrode terminal 102 is formed on the semiconductor element 101. The area of the semiconductor element other than where the aluminum electrode terminal 102 is formed is covered with an insulating film 103 composed of Si oxide film, Si nitrogen film and the like. On the aluminum electrode terminal 102, a projected electrode 104 composed of conductive metallic material such as Au or Cu and the like is formed. On the other hand, a desired circuit pattern 106 and an electrode terminal 107 are formed on the principal surface of circuit substrate 105 composed of insulating material such as resin, ceramic or glass and the like. The electrode terminal 107 is connected to the circuit pattern 106. In flip-chip packaging, the electrode terminal 107 connects electrically with the semiconductor element 101. A projected electrode 104 is electrically connected with the electrode terminal 107 by the conductive adhesive 108. The conductive adhesive 108 contains a powder of conductive metallic material such as Ag, Cu or Ni and the like in the resin. The insulating resin 109 is filled in the space between the semiconductor element 101 and the circuit substrate 105. When the insulating resin 109 is hardened, the semiconductor element 101 and the circuit substrate 105 are bonded by the hardening shrinkage force of the insulating resin 109, and are attracted powerfully and fixed. Consequently, the mechanical strength of connecting the semiconductor element 101 and the circuit substrate 105 of the semiconductor apparatus is enhanced and a stable fixing can be maintained.
A method for producing the conventional semiconductor apparatus as above-mentioned will be explained referring to FIG. 10, which is a flow chart showing the process of producing the semiconductor apparatus. First, a semiconductor element 101, on which a desired element, a wiring and an insulating film 103 are formed by the normal process of producing the semiconductor, is produced. Then the semiconductor wafer, on which a numerous pieces of semiconductor element 101 are formed, is produced. Then, the quality of the semiconductor element 101 is checked by electrical inspection, that is, by contacting the probe, and the projected electrode 104 is formed. After that, the semiconductor wafer is cut into individual semiconductor elements 101. On the other hand, in advance, a desired circuit pattern 106 and an electrode terminal 107 are formed using conductive material such as conductive metal, e.g. Au or Cu and the like on the circuit substrate 105 which is composed of the insulating material. Then the semiconductor element 101 is positioned on the circuit substrate 105 with its face down via conductive adhesive 108 so that the predetermined electrode terminal 107 can be connected electrically with the projected electrode 104. After that, the conductive adhesive 108 is hardened by heat treatment and electrical inspection is conducted to confirm the acting state. After the normal acting state is confirmed, the liquid insulating resin such as epoxy-based resin is filled in the space between the semiconductor element 101 and the circuit substrate 106 by capillary action. After the insulating resin is filled in the space, the insulating resin 109 is hardened by heat treatment and the like, and accordingly the flip-chip packaging is completed.
The semiconductor apparatus in which the flip-chip packaging technique is used was produced according to the above-mentioned production processes.
However, according to the above-mentioned conventional semiconductor apparatus and the method for producing the conventional semiconductor apparatus as shown in FIG. 11, irregularity of the flatness accuracy of the surface of the circuit substrate 105 is caused by the warp, swell and the like in some parts of the circuit substrate 105. Further, there is also the irregularity of the film thickness accuracy of the electrode terminal 107. Consequently, the protruding surface of the electrode terminal 107 at the side of the circuit substrate in the region of one semiconductor element is not positioned at the horizontal surface respectively, and therefore an irregularity of the position of the protruding surface of the electrode terminal 107 at the side of the circuit substrate in the direction of height of the protruding surface is caused.
Consequently, in mounting the semiconductor element 101 with face down, the size of the space between the semiconductor element 101 and the circuit substrate 105 in the concave portion of the circuit substrate 107 is larger than that of other parts of the circuit substrate 107. As a result, the conductive adhesive 108 can not reach to the protruding surface of the electrode terminal 107 positioned in the concave portion of the circuit substrate. Consequently, the electrical connection failure is caused.
It is an object of the present invention to provide a semiconductor apparatus which is stable in quality and has good productivity, and a method for producing the same by connecting electrically the semiconductor element and the circuit substrate more reliably.
In order to achieve the above-mentioned objects, in the semiconductor apparatus of this invention, the flip-chip packaging technique is used for connecting electrically a semiconductor element and a circuit substrate via a projected electrode composed of conductive metallic material formed on an electrode terminal, which is formed on the surface of the semiconductor element where the element is formed, a conductive adhesive and an electrode terminal on the circuit substrate, wherein the individual projected electrode is deformed plastically in the direction of the height so that the distance between a protruding surface of an individual projected electrode and an opposing surface of the individual electrode terminal via the conductive adhesive is unified.
According to the semiconductor apparatus in this invention, the height of the projected electrode is processed appropriately so that the distance between the protruding surface of the individual projected electrode and the opposing surface of the individual electrode terminal via the conductive adhesive is uniform. Consequently, the semiconductor element can be connected electrically with the circuit substrate reliably.
It is preferable that in the semiconductor apparatus, the material of the projected electrode is at least one metallic material selected from the group consisting of Au and Cu.
Furthermore, it is preferable that the distance between the protruding surface of the individual projected electrode and the opposing surface of the individual electrode terminal via the conductive adhesive is in a range of 1 xcexcm to 10 xcexcm.
Furthermore, it is preferable that the flip-chip packaging technique is used for connecting the semiconductor element and the circuit substrate via the electrode terminal formed on the semiconductor element where the element is formed, the conductive adhesive and the projected electrode composed of the conductive metallic material formed on the electrode terminal on the circuit substrate.
In the preferred semiconductor apparatus in which the projected electrode is formed at the side of the circuit substrate, it is preferable that a barrier layer composed of conductive metallic laminated film is formed on the electrode terminal on the semiconductor element where the element is formed.
According to the preferred semiconductor apparatus on which the barrier layer is formed, the corrosion of the electrode terminal formed on the semiconductor element where the element is formed can be prevented.
In the semiconductor apparatus, it is preferable that the height of the projection of the projected electrode is substantially uniform.
In the semiconductor apparatus whose height of the projection of the projected electrode is substantially uniform, it is preferable that the height of the protruding surface of the individual projected electrode is unified by pushing the projected electrode on a flat surface of a hard material before the projected electrode is bonded with conductive adhesive.
In the semiconductor apparatus in which the height of the protruding surface of the individual projected electrode is unified by pushing the projected electrode on the flat surface of the hard material, it is preferable that the pressure on the protruding surface of the projected electrode which is caused by pushing on the flat surface of the hard material is in a range of 1.5xc3x97108 to 5.0xc3x97108 N/m2.
Furthermore, it is preferable that the variation in flatness of the hard material is 4 xcexcm or less over a distance of 20 mm.
According to a first aspect of the method for producing the semiconductor apparatus, a projected electrode is formed on the semiconductor element where the element is formed, a conductive adhesive is transferred on the vertex of the projected electrode and the semiconductor element is pressured from the back when the semiconductor element is mounted on the circuit substrate with its face down. According to that, the projected electrode formed on the semiconductor element is deformed plastically to unify the distance between the protruding surface of the individual projected electrode formed on the semiconductor element and the opposing surface of the individual electrode terminal at the side of the circuit substrate.
According to the first aspect of the method for producing the semiconductor apparatus, the height of the projected electrode can be processed appropriately so that the distance between the protruding surface of the individual projected electrode and the opposing surface of the individual electrode terminal via the conductive adhesive can be unified. As a result, the semiconductor apparatus with high reliability can be produced easily and at a low cost.
In the first aspect of the method for producing the semiconductor apparatus, it is preferable that the pressure on the protruding surface of the projected electrode caused by pushing the semiconductor element from the back is in a range of 1.5xc3x97108 to 5.0xc3x97108 N/m2.
Furthermore, it is preferable that after the projected electrode formed on the semiconductor element is deformed plastically, the conductive adhesive is transferred to the vertex of the individual projected electrode formed on the semiconductor element and the semiconductor element is mounted on the circuit substrate with face down again.
In the method for producing the preferred semiconductor apparatus in which the projected electrode is deformed plastically, and then the semiconductor element is mounted on the circuit substrate again, the semiconductor element is not pressured substantially when the semiconductor element is mounted on the circuit substrate its with face down. Therefore the shift of the position of the semiconductor element and the circuit substrate can be prevented.
According to a second aspect of the method for producing the semiconductor apparatus, after a projected electrode is formed on the electrode terminal formed on the circuit substrate, the height of the protruding surface of the individual projected electrode is unified by pushing the projected electrode to the flat surface of the hard material, the conductive adhesive is transferred to the vertex of the individual projected electrode and the semiconductor element is mounted on the circuit substrate with its face down.
According to the second aspect of the method for producing the semiconductor apparatus, a step of pressuring the semiconductor element is not present. Therefore the damage inflicted on the semiconductor element can be decreased.
In the second aspect of the method for producing the semiconductor apparatus, it is preferable that the pressure which is caused by pushing the projected electrode to the flat surface of the hard material to apply to the protruding surface of the projected electrode is in a range of 1.5xc3x97108 to 5.0xc3x97108 N/m2.
Furthermore, it is preferable that the variation in flatness of the hard material is 4 xcexcm or less over a distance of 20 mm.